Ultra-low thermal conductivity in graphene nanomesh

Abstract

Graphene nanomesh (GNM), a new nanostructure of graphene, has attracted extensive interest recently due to the promising chemical, electronic and photonic applications. In this paper, another important property-thermal conductivity is systematically investigated by using molecular dynamics simulations. The thermal conductivity (κ) is found to be extremely low, up to more than 3 orders lower than the pristine single layer graphene. Roughly, κ decreases exponentially with increasing porosity and linearly with decreasing neck width, and is not temperature sensitive in the range of 300 K to 700 K. κ of GNMs is found to be even up to 200 fold lower than the graphene nanoribbons (GNR), a potential thermoelectric material, of the same neck width or boundary-to-area ratio. The extremely low κ in the GNM makes it a potential candidate for thermoelectrics. The phonon participation spectra show that the low κ in GNM is due to the localization and phonon back scattering around the nanopores. We also find that the phonon coherence in two dimensional superlattice GNM indeed exists, but is not as important as in the one dimensional superlattices. The isotope effect is negligible. The thermal conductivity reduction by edge passivation increases with increasing neck width and porosity.

Carbon-Based Materials for Thermoelectrics

“…On one hand, nanoholes can hinder phonon transport significantly through phonon scattering. Though not mentioned in [97], one should also expect significant phonon localization [55,56] near the edges of the nanoholes, as confirmed by Feng and Ruan [83], no matter whether they are terminated with hydrogen or not. On the other hand, as revealed by Sadeghi et al, the nanoholes suppress the electron transmission far above or far below the Advances in Condensed Matter Physics Fermi energy, but the high transmission in the vicinity of Fermi level is preserved [97].…”

“…This hypothesis was seemingly formed based on the phonon band folding mechanism [84,92] as well as Hao et al Monte Carlo phonon transport simulations [99]. Recently, Feng and Ruan conducted MD simulations and spectral energy density analysis to investigate phonon transport in GNMs, for which they found a 200-fold lower L than corresponding GNRs with the same (neck) width and boundary-to-area ratio [83]. The ultralow L of GNMs is attributed to the localization of phonons in the vicinity of the nanopores, as evidenced by the phonon participation ratio and backscattering of phonons.…”

“…However, there exist various strategies for reducing L of graphene through nanoengineering, for example, by introducing isotopes [76][77][78], vacancies [79][80][81][82], nanoholes [83,84], dislocations, or grain boundaries. Cutting graphene into graphene nanoribbon was also found to be effective in reducing its L , which arises from a combination of enhanced phonon-boundary scattering [85][86][87] and phonon-edge localization [37,55,56].…”

Nanoperforated graphene with alternating gap switching for optical applications

“…Extensive approaches have been used to tackle with this problem including dimensionality reduction tailoring, [6][7] surface modification, 8 heteroatom doping, 9 layered stacking, 10 and exerted to external potential. 11 In addition to those schemes, however recently, the topic about graphene superlattice with nanoholes, [12][13][14] also dubbed graphene nanomesh (GNM), [15][16][17][18][19][20][21][22][23] or graphene antidote lattice (GAL), [24][25][26][27][28][29][30][31] attracts substantial research interest since a non-vanishing gap is introduced in certain unique structures. Due to the effective tunability of intrinsic graphene bang gap, these porous graphene structures possess potential applications in spintronics, 12,14 thermoelectronics, 23,27 waveguiding devices, 29,31 and transistors.…”

“…11 In addition to those schemes, however recently, the topic about graphene superlattice with nanoholes, [12][13][14] also dubbed graphene nanomesh (GNM), [15][16][17][18][19][20][21][22][23] or graphene antidote lattice (GAL), [24][25][26][27][28][29][30][31] attracts substantial research interest since a non-vanishing gap is introduced in certain unique structures. Due to the effective tunability of intrinsic graphene bang gap, these porous graphene structures possess potential applications in spintronics, 12,14 thermoelectronics, 23,27 waveguiding devices, 29,31 and transistors. [15][16][17][18][19]32 GNM based field-effect transistors perform some improved electronic properties than sliced graphene nanoribbon (GNR) devices, 16 it could deliver 100 times higher drive currents, and demonstrated comparable tunable ON/OFF ratios than similar individual GNR devices.…”